It is an electron beam. In the 1890s, the latter part of the 19th century a very fashionable word was "ray."

那是个电子束，在十九世纪九十年代，就是19世纪末,一个很时髦的词汇-“光线“

麻省理工公开课 - 固态化学导论课程节选

So rather than calling this an electron beam, this was called a cathode ray.

因此我们最好别叫它电子束，而是阴极射线。

麻省理工公开课 - 固态化学导论课程节选